Thread: I need help

hey,
I`m new in this forum and this is my first experiance in such forums....
Something about me: my name is Marijana, I`am a 19 years old and i am study...and don`t know what to say another...
Now I need help from you.My code below is for multipling two binary number in IEEE 735 standard and I have this

package proekt2;
 
public class ArrayUtils{
 
    static String[] lookupTable = {
        "0+0+0=00",
        "0+0+1=01",
        "0+1+0=01",
        "0+1+1=10",
        "1+0+0=01",
        "1+0+1=10",
        "1+1+0=10",
        "1+1+1=11",
    };
   public  static String lookup(char b1, char b2, char c) {
        String formula = String.format("%c+%c+%c=", b1, b2, c);
        for (String s : lookupTable) {
 
            if (s.startsWith(formula)) {
                return s.substring(s.indexOf("=") + 1);
 
            }
        }
        throw new IllegalArgumentException();
 
    }
   public static String zeroPad(String s, int length) {
        while (s.length() < length) {
            s = "0" + s;
        }
        return s;
    }
    public static String add(String s1, String s2) {
        int length = Math.max(s1.length(), s2.length());
        s1 = zeroPad(s1, length);
        s2 = zeroPad(s2, length);
        String result = "";
        char carry = '0';
        for (int i = length - 1; i >= 0; i--) {
            String columnResult = lookup(s1.charAt(i), s2.charAt(i), carry);
            result = columnResult.charAt(1) + result;
            carry = columnResult.charAt(0);
        }
        if (carry == '1') {
            result = carry + result;
        }
        return result;
    }
 
 public static String multiply(String s1, String s2) {
    String result = "";
    String zeroSuffix = "";
    for (int i = s2.length() - 1; i >= 0; i--) {
        if (s2.charAt(i) == '1') {
            result = add(result, s1 + zeroSuffix);
        }
        zeroSuffix += "0";
    }
    return result;}
}

i call in another class with in this way

String proiz=null;
  int pBrojac=0;
    System.out.print(ArrayUtils.add(binaren, binaren2));
    System.out.println();
    System.out.print(ArrayUtils.zeroPad(proiz, pBrojac));
    System.out.println();
    System.out.print(ArrayUtils.multiply(binaren, binaren2));

and the mistake is this

Exception in thread "main" java.lang.IllegalArgumentException
at proekt2.ArrayUtils.lookup(ArrayUtils.java:24)
at proekt2.ArrayUtils.add(ArrayUtils.java:40)
at proekt2.Kraj.main(Kraj.java:188)
Java Result: 1

yes, i know that there is the problem but u don`t know how to repair it